Geoscience Reference
In-Depth Information
0
1000
1000
km
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Figure 28.10
Present and projected boundaries of summer sea-ice, permafrost and tree line in the Arctic.
of the United States and Canada suggests that ecosystems
will experience both latitudinal and altitudinal changes.
One estimate for Glacier National Park, Montana,
estimates that forests will advance upslope 2 m per year
by 2050. Other estimates for mountain areas globally
suggest rates of 1 m in altitude per year for small mammals
and insects, which obviously have greater speeds of
dispersal. Research in Yellowstone National Park,
Wyoming, suggests that the ranges of alpine flowers and
alpine conifers would decrease, with the strong possibility
of regional extinctions due to competition from more
vigorous, lower-altitude trees. On the other hand, new
communities not currently found in the park would
become established, so that overall it is likely that that
there would be no loss of biodiversity.
CONCLUSION
It seems fitting to conclude this topic with a return to
issues of concepts and methods that were raised in
Chapter
1.
Physical geography has come a long way since the
discussions of catastrophism and uniformitarianism of
previous centuries. Physical geographers now perform
many useful tasks for society at large. An important one
is the ability to offer predictions about environmental
futures, or scenarios in today's jargon, which has brought
an exciting range of methodologies that are helping to
assess interactions between future climate change and
ecosystems:
